The Right Formula
by GoldenHeart92
Summary: "Really? Our life depends on whether or not we can solve a Rubik's cube?"


**Disclaimer: I don't own anything. Never have, never will**

**A/N: Yet another one-shot with my favorite pairing ever! Enjoy.**

"Alright Spaceman, spit it out. What have we done this time?"

"Really, Donna, I'm not sure."

"Well hurry up and figure it out!" she screeched as she paced the length of their cell.

She and the Doctor had simply been strolling along, browsing through some of the stalls when they had suddenly been taken into custody by what she could only assume was the police force of this planet. They'd had their coats taken and been hauled into a cell but given no reason as to their detainment.

Of course they couldn't just have one normal day without offending some planet and its inhabitants. That was never going to happen. Just like she was never going to get her beach.

They waited in silence for about an hour before their cell was approached by one of the aliens.

"Greetings. I am sorry for your abrupt and unexplained imprisonment, but I need your help."

The Doctor jumped up from his position on a stone bench and bounded over to the bars of the cell.

"Oh that's alright, no harm done. I'm the Doctor, by the way. And this is Donna. Now, what seems to be the problem, Mr.…?"

"Names are of no importance, Doctor. However, I am the ruler of this land and you may address me as such. What is important is that you help me solve this problem."

"Okay then, what seems to be the problem your highness?"

"Let me start at the beginning: several years ago, we had off-worlders much like yourselves visit our planet. We welcomed them and learned much about their culture as we taught them of ours. They had many trinkets with them, and offered some of them to me as a token of their appreciation. Among these gifts was a cube. Each side had a different color applied to it. The leader of their group explained that it was a puzzle on his world and showed me how to turn the smaller cubes to mix the colors and then put them back together. I was delighted by this, and shortly after the travelers left I mixed the colored cubes as they had shown me. But then there was a problem."

"Let me guess," the Doctor interjected, "you were unable to match the colors back to their original sides."

The alien seemed shocked that the Doctor knew this. "Yes! That is exactly what happened. How did you know?"

"Lucky guess. Can I see it?"

"Of course." He pulled the cube from a pocket in his outfit and handed it to the Doctor.

"It has tormented me constantly and I've not had a decent night's sleep in years. You must fix this for me, Doctor. As soon as you have, you will both be free to go."

The Doctor's face adopted a look of slight worry.

"And, just out of curiosity, what exactly would happen if I were unable to solve it?"

The monarch looked slightly aggrieved, "Then I'm afraid you and your wife would be put to death."

They started up the usual routine:

"Oh… we're not married-."

"At all-."

"Never-."

"Never ever."

Surprise was evident on the alien's face, "I apologize. I just assumed… Anyhow, you and your friend will be put to death."

"But that's not fair!" Donna piped up from behind the Doctor, which earned a glare thrown her way by the monarch.

"This is your technology, therefore it is perfectly fair. As the creator of this puzzle cube, your people should be aware of how to solve it. You have one day. I shall be back in the morning to evaluate your progress." And with that he strode away from the cell, leaving the two travelers with the cube.

"Really?" Donna asked in disbelief once they were alone again, "our life depends on whether or not we can solve a _Rubik's cube?_ Now I've seen everything." She went and took a seat on the stone bench that the Doctor had previously been occupying.

The Doctor continued to stand by the door to their cell, Rubik's cube in hand. He made no move to align the colors back to their normal positions.

"What are you doing? Hurry up and solve that thing so we can get out of here."

"Donna…"

"I mean I've never heard of such a thing. Sentenced to death over something as silly as a puzzle."

"Donna…"

"Of course I don't know why I'm surprised. God knows it's not the weirdest thing I've seen since traveling with you. You remember when-."

"Donna!"

"What!"

"I can't."

She looked shocked, "What do you mean you can't? Use your highly evolved Time Lord brain and solve it."

"I don't know how."

She simply stared at him, mouth agape, as he stared apologetically.

"I hope you're joking."

"I'm sorry, Donna."

"You're the most intelligent being in the universe. What's so hard about that little thing?"

"Do you know how many different combinations there are? Millions of them. I mean, I can try to experiment to find the right algorithms, but it's going to take me a lot longer than one day."

He turned back to face the outside of their cell and began muttering to himself, experimentally turning the sides and trying to solve the puzzle before turning and making his way to sit beside Donna.

"Can't you just use your sonic screwdriver on it?"

"I could if I had it with me. It's in my coat pocket." He fiddled with the cube a little more, but was still unable to solve it.

"Doctor, let me see it."

He tossed her the cube before standing back up again to pace the room, continuing to mutter to himself about formulas and patterns. After about a minute he was startled out of his internal ramblings,

"Doctor…"

"Not now Donna. I'm thinking."

He heard her mumble something about rude aliens before something hard connected with the back of his skull and land with a thud. Rubbing the back of his head, he looked down at the ground to see the Rubik's cube- completely solved. His gaze snapped from the puzzle to his companion.

"What… how did you…?"

"When I was younger, my mates and I used to race each other with those things to see who could finish first. Guess I never really forgot how to solve it." She told him with a shrug.

"Well why didn't you tell me?"

"What, you mean all of five seconds ago? When you were pacing around and muttering like a nut job and wouldn't let me speak?"

The doctor had the good graces to look sheepish, "Yeah, sorry about that. But did you really have to hit me over the head with it?"

"I barely threw it. It was more of a toss, really. Anyways, I doubt it did any damage. You have a head harder than anyone else I've ever met."

He decided to change the subject before she could bruise his ego any further, "What do say we get out of here?"

"I like the sound of that."

The doctor turned to face the outside of their cell, yelling to one of the guards, "Oi, you can tell his Majesty that we have solved his puzzle and now demand our release." He held up the cube to prove his point and the guard walked off with a nod of acknowledgement.

Finally, the Monarch made his way to their cell and addressed the Doctor.

"Ahh, so I see you've solved the puzzle. That was quicker than I expected. Well done."

The Doctor spoke up, "Actually, it was Donna here."

"Yep, it was me. Now let us go."

"Of course; and know that you will always be welcome here."

After saying their farewells and collecting their coats, they made their way back to the safety of the TARDIS and the Doctor put them into the vortex.

"Sooo… you can solve a Rubik's cube, huh?"

"Yep." Donna replied distractedly.

The Doctor nodded several times before speaking up again, "You think you might teach me your method?"

She gave a long sigh, the kind one might give when they were about to explain something obvious to a small child, "I knew this would happen. You can't stand to have someone else know something that you don't."Doctor, this is most likely the _only_ thing in the entire universe that I know and you don't. Do you really think I'm going to give away that one piece of information?"

Silence descended into the console room for several seconds,

"Please?"

"No."

"I'll take you anywhere you want to go."

"You'll do that anyway."

"Come on, Donna. Pleeeease." He whined.

Alright, Spaceman. You said you'd take me anywhere I want to go. Well, I want to go to Chiswick. Now."

His whining stopped instantly as his mouth slammed shut with an audible click.

"I'm sorry. I won't ask again. You're right, it's not fair of me to ask you to teach me when I know all this stuff I don't tell you about and I won't bring it up again, just please don't leave!"

"Leave? I'm not leaving you Dumbo. We're just stopping to get you a Rubik's cube so you learn how to solve it… on your own."

"Oh." The relief in his voice was palpable.

"And there's no chance that you might teach me?"

"None at all. You're a genius, as you so often like to point out. I'm sure you can figure it out. And once you do, I'll race you."

"I'll hold you to that." He promised as he punched in the coordinates to Chiswick.

_END_

**Hope you guys enjoyed. Thanks for reading.**

**-Goldenheart**


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